The invention relates to frequency converters provided with a brake chopper switch.
It is known to connect a brake chopper switch and a brake resistor to direct-voltage intermediate circuits of frequency converters in such a manner that, when the brake chopper switch is in its closed position, current flows from the positive branch of the direct-voltage intermediate circuit to the negative branch of the direct-voltage intermediate circuit via the brake resistor. Such a connection allows the braking of a motor supplied by the frequency converter. The brake resistor may be an internal or external component. An internal brake resistor may be a component integrated into the frequency converter, and an external brake resistor may be a detachably attachable component. The frequency converter may comprise a positive terminal and a negative terminal, between which the external brake resistor may be connected.
It is also known to use the direct-voltage intermediate circuit of a frequency converter for supplying direct current out of the frequency converter. It is also possible to arrange the frequency converter in such a manner that its direct-voltage intermediate circuit may be connected to the intermediate circuit of another frequency converter to provide a common DC bus connection.
To provide a frequency converter with both terminals allowing the connection of an external brake resistor and poles allowing the supply of direct-voltage power out of and/or into the direct-voltage intermediate circuit is problematic, because the great number of terminals requires a lot of space and increases manufacturing costs.